Adhesive tapes

ABSTRACT

An adhesive tape for electronic parts, comprising (a) a heat resistant base film, and (b) an adhesive layer laminated on at least one surface of said base film, said adhesive layer comprising 
     (i) a resol type phenol resin, and 
     (ii) an acrylonitrile/butadiene copolymer, 
     in a proportion of from 100 to 500 parts by weight of said resol phenol resin per 100 parts by weight of said acrylonitrile/butadiene copolymer, said resol type phenol resin being selected from the group consisting of bisphenol A type resins, alkylphenol type resins, phenol type resins and their co-condensed type phenol resins which contain as the phenol component at least one member selected from the group consisting of bisphenol A, alkylphenols and phenol.

This is a continuation of application Ser. No. 08/417,457, filed Apr. 5,1995, abandoned, which is a continuation of application Ser. No.08/137,608, filed Oct. 14, 1993, abandoned which is a division ofapplication Ser. No. 07/814,236, filed Dec. 23, 1991, now issued U.S.Pat. No. 5,277,972, issued Jan. 11, 1994, which is a continuation ofapplication Ser. No. 07/414,012, filed Sep. 28, 1989, now abandoned.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to adhesive tapes for electronic parts, forexample resin-sealed-type semiconductor devices, in particular, thoseused for fixing inner lead pins for lead frames in resin-sealed-typesemiconductor devices.

2. Description of Prior Art

Adhesive tapes used in resin sealed semiconductor devices include tapesfor fixing lead frames, die pad tapes, tab tapes and the like. In thecase of, for example, adhesive tapes for fixing lead frames, theadhesive tapes are used for fixing inner lead pins and for increasingthe yield and productivity of the lead frames themselves and of wholeassembly procedures for the manufacture of the semiconductor devices.Therefore, they are generally attached on the lead frames by themanufacturer of the lead frames and conveyed to the manufacturer ofsemiconductor devices where they are sealed with a resin after mountingintegrated circuits (IC's). In other words, the adhesive tapes areincorporated in the package of the semiconductor devices. Therefore,adhesive tapes, for example, those for fixing the lead frames, arerequired to have adhesion strength high enough not only at roomtemperature immediately after the taping but also after heating in ICassembly procedure as well as have general reliability for the level ofsemiconductors and operability or ease of handling at the time oftaping.

Heretofore, there have been used as the adhesive tapes for fixing innerlead pins of the lead frames various adhesive tapes including, forexample, those composed of a base film such as polyimide film on whichan adhesive is coated which comprises polyacrylonitrile resin,polyacrylate resin or synthetic rubber resins such asacrylonitrile/butadiene copolymers alone or modified or mixed with otherresins, and converted to the B stage.

As is well known, semiconductor devices are subjected to reliabilitytests under severe conditions such as in pressure cooker test(hereafter, "PCT"). Naturally, the adhesive tapes for fixing the leadframes in the resin molded package must surely have enough reliabilityunder the same conditions. Among various reliabilities which thematerials used in the semiconductor devices must have, particularlyimportant for adhesive tapes for fixing lead frames is electric currentleak characteristics. This corresponds to a phenomenon that electriccurrent flows through the tape portion where the adhesive tape forfixing lead frame is attached, and smaller quantity of the electriccurrent means better electric current leak characteristics.

On the other hand, the degree of integrity of semiconductor elements isrecently improving remarkably and also miniaturization of semiconductorshas been proceeding rapidly, resulting in that the number of lead framepins has increased and the respective inner lead pins of the lead frameshave become thinner. There is a tendency for the distance between thepins to become shorter. This leads to more severe requirement foraccuracy of the positioning of the respective pins.

Under the circumstances, the semiconductor devices with the conventionaladhesive tapes for fixing the lead frames do not show sufficientinsulation properties between the inner lead pins and thus theirelectric current leak characteristics are poor. Moreover, it has beenquite unclear which factors the electric current leak characteristics ofthe conventional adhesive tapes depend upon and how they can beimproved.

SUMMARY OF THE INVENTION

Accordingly, it is an object of this invention to provide adhesive tapeshaving improved electric current leak characteristics for use withelectronic parts.

With view to overcoming the defects of the conventional adhesive tapes,intensive investigation has been made by the present inventors on therelationship between the composition and various properties of theadhesive tapes and the electric current leak characteristics using aheat resistant base film having approximately acceptable electriccurrent leak characteristics as a support and an adhesive layer composedof generally acrylonitrile/butadiene copolymer/phenolic resin coated onthe surface of the base film. As the result, it has now been found thatthe above object can be achieved using adhesive tapes with specifiedcompositions.

This invention is based on the above discoveries and provides anadhesive tape for electronic parts, comprising

(a) a heat resistant base film, and

(b) an adhesive layer laminated on at least one surface of said basefilm, said adhesive layer comprising

(i) a resol phenol resin, and

(ii) an acrylonitrile/butadiene copolymer,

in a proportion of from 100 to 500 parts by weight of said resol phenolresin per 100 parts by weight of said acrylonitrile/butadiene copolymer,

said resol phenol resin being selected from the group consisting ofbisphenol A resins, alkylphenol resins, phenol resins and theirco-condensed phenol resins which contain as the phenol component atleast one member selected from the group consisting of bisphenol A,alkylphenols and phenol.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematical cross-sectional view of the adhesive tape forelectronic parts according to this invention, in which the adhesivelayer is laminated on one surface of the heat resistant base film;

FIG. 2 is a schematic cross-sectional view of the adhesive tape forelectronic parts according to this invention, in which the adhesivelayer is laminated on one surface of the heat resistant base film and aprotective layer is further laminated on the adhesive layer;

FIG. 3 is a schematic cross-sectional view of the adhesive tape forelectronic parts according to this invention, in which the adhesivelayer is laminated on each surface of the heat resistant base film;

FIG. 4 is a schematic cross-sectional view of the adhesive tape forelectronic parts according to this invention, in which the adhesivelayer is laminated on each surface of the heat resistant base film and aprotective layer is further laminated on the respective adhesive layers;

FIG. 5 is a plan view of a lead frame illustrating the state in which anadhesive tape is attached on the lead frame; and

FIGS. 6(a) and 6(b) are partial enlarged view of the lead frame shown inFIG. 5.

FIG. 7 is a view illustrating the method of peeling tests used inexamples of this invention.

DETAILED DESCRIPTION OF THE INVENTION

Hereinafter, this invention will be described in detail with referenceto the attached drawings, in which FIGS. 1 through 4 are schematicalcross-sectional views of adhesive tapes for electronic parts accordingto this invention. In FIGS. 1 and 2, a heat resistant base film 1 islaminated on one surface thereof with an adhesive layer 2. In FIG. 2, aprotective layer 3 is further laminated on the surface of the adhesivelayer 2. In FIGS. 3 and 4, adhesive layers 2 and 2' are laminated on theopposite surfaces of the heat resistant base film 1. In FIG. 4,protective layers 3 and 3' are laminated on the adhesive layers 2 and2', respectively.

The construction of the respective layers of the adhesive tape of thisinvention will be explained hereafter.

A. Heat Resistant Base film

As the heat resistant base film, there can be used organic base film,more particularly heat resistant base films composed of polyimides,polyether-ether-ketones, polyetherimides, polyphenylene sulfides, andpolyparabic acid, and composite heat resistant base films such as epoxyresin-glass cloth, and epoxy resin-polyimide-glass cloth, which basefilms have a thickness of from 5 to 300 μm, preferably from 10 to 150μm, more preferably 12.5 to 150 μm, and most preferably 25 to 75 μm.

B. Adhesive Layer

The adhesive layer is composed of a mixture of anacrylonitrile/butadiene copolymer (hereafter, "NBR") and a resol phenolresin.

As NBR, there can be used a nitrile rubber having a relatively highnitrile content as high as from 10 to 45% by weight, preferably from 20to 45% by weight and a molecular weight of from 20,000 to 1,000,000,preferably from 100,000 to 500,000. The NBR may optionally contain avulcanizing agent such as quinones, dialkyl peroxides, and peroxyketalsin order to exhibit self cross-linking property upon heating.

The resol phenol resin includes bisphenol A resins, alkylphenol resins,phenol resins and their co-condensed phenol resins which contain as thephenol component at least one member selected from the group consistingof bisphenol A, alkylphenols and phenol.

As the resol phenol resin in which the phenol component is bisphenol A,there can be used those which are synthesized using bisphenol A as astarting compound and which have the following basic skeleton and whosesoftening point as measured by the ring and ball method is from 70° to90° C. ##STR1##

As the resol phenol resin in which the phenol component is thealkylphenol, there can be used those which are synthesized using as astarting compound an alkylbenzene having an alkyl group mainly at theortho- or para-position to the phenolic hydroxyl group. Examples of thealkyl group include a methyl group, an ethyl group, a propyl group, at-butyl group, a nonyl group, and the like. For example, there can beused p-t-butylphenol resol phenol resins which have the following basicskeleton and whose softening point as measured by the ring and ballmethod is from 80° to 100° C. ##STR2##

The resol phenol resins in which the phenol component is phenol arethose which are synthesized using unsubstituted phenol and formaldehydesas starting compounds.

When the above-described resol phenol resins are used in the adhesivelayer, the resulting adhesive tapes exhibit excellent operability andadhesion and also good electric current leak characteristics.

In the adhesive layer of the adhesive tape of this invention, the phenolcomponent of the resol phenol resin may contain other phenol components,for example, phenol resins of co-condensed derived from p-phenylphenolor biphenyl phenols. Also, a small amount of novolak type phenol resinor epoxy resin may be blended with the resol type phenol resin.

Fillers can be mixed with the resol type phenol resins, if desired.

The proportion of the resol type phenol resin to NBR in the adhesivelayer is from 50 to 500 parts by weight, preferably from 100 to 500parts by weight, more preferably 100 to 300 parts by weight, per 100parts by weight of NBR. When the content of the resol type phenol resinis less than 50 parts by weight per 100 parts by weight of NBR, the leakcurrent value is too high to be acceptable and when it is more than 500parts by weight per 100 parts by weight of NBR, adhesive tapes havingsufficient adhesion and good operability cannot be obtained.

In this invention, the adhesive layer having the above-describedcomposition has a dry and after B-stage coating thickness of from 2 to50 μm, preferably 7 to 30 μm, and more preferably 10 to 30 μm.

C. Protective layer

The adhesive tape for electronic parts of this invention may be providedwith a protective layer on the adhesive layer, if desired. As theprotective layer, there can be used polyethylene film, polyethyleneterephthalate film, polypropylene film, fluororesin film, paper and thelike, which may be imparted peeling property with silicone resin or thelike, if desired. The protective layer has a thickness of from 1 to 200μm, preferably from 5 to 100 μm, more preferably from 10 to 100 μm, andmost preferably from 12.5 to 50 μm.

When the adhesive tape for electronic parts of this invention has aconstruction such that the adhesive layer is laminated on one surface ofthe heat resistant base film, the tape preferably has the followingcharacteristics (1), (2) and (3).

(1) The electric conductivity of an extract containing organic andinorganic ionic impurities extracted from the adhesive tape under theconditions set forth below is not higher than 70 μs/cm.

(2) The concentration of sulfate ions in the adhesive tape forelectronic parts is not higher than 300 ppm.

(3) When the surface of the heat resistant base film is brought incontact with the molding compound, the adhesive tape has an adhesionstrength of not lower than 200 g/1.5 cm upon 180° peeling test.

In this invention, the above-described characteristics (1), (2) and (3)refer to those measured under the following conditions.

1) Conditions for Measuring Electric Conductivity

1-a) Conditions for Pretreatment of Tapes

The adhesive tape, after stripping off the protective layer, if any, iscut to pieces of a size of about 1 cm square, with care lest the tapeshould be contaminated with ionic impurities.

1-b) Conditions for Extraction

1-b-1) In a sufficiently washed heat resistant round bottom glass flaskis charged 10 g of a sample and 100 g of deionized water having anelectric conductivity of not higher than 5 μs/cm is added thereto.

1-b-2) To the glass flask is fitted a sufficiently washed refluxcondenser and the content is heated at 100° C. and left to stand for 20hours.

1-c) Conditions for Measurement

The electric conductivity of the extract is measured using aconductometer.

2) Conditions for Measurement of Concentration of Sulfate Ions

2-a) Conditions for Pretreatment of Tapes

The adhesive tape, after stripping off the protective layer, if any, iscut to pieces of a size of about 3 cm square, with care lest the tapeshould be contaminated with ionic impurities.

2-b) Conditions for Preparing Samples for Measurement

The sample (1 g) after the above-described pretreatment is burnt byoxygen bomb or cylinder method and absorbed in 25 ml of deionized waterto form a sample solution.

2-c) Conditions for Measurement

The concentration of sulfate ions in the sample solution is determinedby means of ion chromatography, and the results obtained are convertedinto the concentration of the sample.

3) 180° Peeling Test

3-a) Preparation of Samples for Measurement

3-a-1) After peeling off the protective layer, if any, the sample tapeis adjusted to a size of 15 mm in width×150 mm in length.

3-a-2) On a metal plate as a support is placed a molding compound beforecuring so as to have a uniform thickness.

3-a-3) On the surface of the molding compound is bonded the sample tapeprepared in 3-a-1) above at its surface to be measured, and is heated at120° C., followed by pressing with a roll of a self-weight of 2 kg.

3-a-4) The sample prepared in 3-a-3) above is heated at 175° C. for 5hours in a drier to cure the molding compound to form a sample formeasuring adhesion to the molding compound.

3-b) PCT Conditions

Using a saturated type pressure-cooker tester, the above-describedsample is treated for 50 hours under the conditions of 121° C. and 2atm.

3-c) Method for Measurement

The 180° peeling strength of the sample is measured using a universaltesting machine.

In the adhesive tape for electronic parts of this invention, itselectric current leak characteristics is excellent when theabove-described characteristics are satisfied. For example, satisfactoryelectric current leak characteristics are obtained when the adhesivetape is applied to quad flat package (QFP) with not less than 168 pinsand the like. In addition, when the above-described characteristics (3)is satisfied, the fluctuation of the measured values of the electriccurrent leak can be minimized.

DESCRIPTION OF PREFERRED EMBODIMENTS

I. In a preferred embodiment this invention, a combination of theacrylonitrile/butadiene copolymer having a specified molecular weightdistribution and a specified resol phenol resin is used.

That is, as the resol phenol resin is used a resin selected from thegroup consisting of bisphenol A resins, alkylphenol resins and theirco-condensed phenol resins which contain as the phenol component atleast one member selected from the group consisting of bisphenol A, andalkylphenols. On the other hand, as the acrylonitrile/butadienecopolymer, there is used one which has a number average molecular weight(MN) of from 20,000 to 200,000 and the ratio of its weight averagemolecular weight (MW) to its number average molecular weight (MN) is inthe range of MW/MN≧2.5.

In this embodiment, the molecular weight is measured by gel permeationchromatography (GPC) under the conditions shown in Table 1 below.

                  TABLE 1                                                         ______________________________________                                        Item        Conditions                                                        ______________________________________                                        Eluant      Tetrahydrofuran                                                   Detector    RI                                                                Column      SHODEX GPC KF-80M X 2 (Hard, spherical                                        porous polystyrene gel)                                           Temperature Room temperature                                                  Method of   Calibration curve is prepared standard                            determining polystyrene gel manufactured by Toyo                              calibration Soda Manufacturing Ltd. having the                                curve in terms                                                                            following molecular weights:                                      of polystyrene                                                                            3,840,000, 775,000, 107,000, 16,700,                                          2,800.                                                            ______________________________________                                    

When the number average molecular weight of the acrylonitrile/butadienecopolymer is less than 20,000, the surface of the adhesive layer afterbeing converted to B-stage becomes relatively sticky and the improvementin the surface property is not noticeable. On the other hand, when it ismore than 200,000, improvement in the adhesion of the adhesive tape,particularly that when the adhesive tape is bonded at low temperatures,is unsatisfactory. Also, no further improvement in the adhesion isobtained with the ratio of the weight average molecular weight to thenumber average molecular weight (MW/MN) being outside the above-definedrange.

In this embodiment, the acrylonitrile/butadiene copolymer may have oneor more peaks of GPC chromatogram in its molecular weight distribution.

Also, in this embodiment, it is preferred to use the resol phenol resinin an amount of from 50 to 300 parts by weight per 100 parts by weightof the acrylonitrile/butadiene copolymer. With the content of the resolphenol resin per 100 parts by weight of NBR being less than 50 parts byweight, the blocking of the surface of the adhesive layer increases andwhen it is more than 300 parts by weight, decrease in the adhesionstrength is observed.

Other conditions may be the same as described above.

In this embodiment, among various properties required for the adhesivetapes for use in resin sealed semiconductor devices, are particularlyimproved the adhesion strength immediately after taping and that afterthermal hysteresis, which is encountered by the adhesive tapes attachedon the lead frame when the semiconductors are subjected to die bondingprocedure in which the semiconductor chips are bonded to the lead framesat a temperature of from 150° to 250° C. for from 1 to 3 hours or whenthey are subjected to wire bonding procedure in which the extreme pointof the inner lead of the lead frame is connected to the wiring pad onthe semiconductor chip with a gold wire at a temperature of from 150° to350° C. for from about 1 to about 30 minutes.

II. In another preferred embodiment, the heat resistant base film isused which has additionally the following properties.

Coefficient of thermal expansion: an average coefficient of linearthermal expansion along the width thereof at from 20° to 300° C. (asmeasured according to ASTM D-696-44) of from 0.4×10⁻⁵ to 2.5×10⁻⁵cm/cm/° C.

Degree of thermal shrinkage: coefficient of dimensional change along thewidth thereof after heating at 300° C. for 3 minutes (as measuredaccording to JIS C2318-6.3.5) being not higher than 0.1%.

(1) Coefficient of thermal expansion

As the material for the heat resistant base film, the same material asdescribed above can be used. However, the following treatments areconducted for obtaining the average coefficient of linear thermalexpansion defined as above because various organic films generally haveaverage coefficient of thermal expansion at from 20° to 300° C. which isin the range of 1.0×10-5 to 15×10-5 cm/cm/° C., and therefore almost allof them except for only a part of them have the average coefficientoutside the above-described range required for this preferredembodiment.

(1-i) An inorganic filler is added to the organic base film.

(1-ii) As the main component material for constituting the organic basefilm, there is used one having a low coefficient of thermal expansion,for example, a polyimide based material containing a repeating unithaving the following formula: ##STR3## (2) Degree of Thermal Shrinkage

Generally, the thermal shrinkage of various organic films is caused bythe following two causes.

(2-1) In the organic films based on epoxy resin, polyimide or the likethermosetting resin, heat curing reaction of the resin constituting thefilm is not sufficient and therefore the film shrinks upon subsequentheating.

(2-2) When the resin is stretched to form a film, deforming stress isgenerated in the film due to stretching or the like, and the deformingstress is relaxed by heating to cause the film to shrink.

Therefore, the thermal shrinkage due to the heating during the assemblystep can be reduced to a value within the above-described range bysubjecting the film to preliminary heat treatment. The heat treatmentcan be conducted, for example, by passing the organic films through twoopposing infrared heaters or passing between a plurality of heatedrollers heated at a temperature of from 280° to 360° C. for from 1 to 10minutes with keeping the films in contact with the surface of therollers.

According to this preferred embodiment, the so-called lead shift iscaused by the deviation of the positions of the inner lead pins which isbecause of the thermal hysteresis encountered during the assemblyprocedure of the semiconductor devices as explained previously.

The lead shift phenomenon is explained with reference to the attacheddrawings in which FIG. 5 illustrates a 4-directional multi-pin leadframe on which an adhesive tape for fixing the lead frame is attached.In FIG. 5, the adhesive tapes 11a and 11b are attached to the inner leadpins 12 so as to substantially form a square. FIGS. 6(a) and 6(b) arepartial enlarged views of the lead frame shown in FIG. 5. FIG. 6(a)shows the state before the lead frame undergoes the thermal hysteresis,and FIG. 6(b) shows the state after the lead frame undergoes the thermalhysteresis. In FIGS. 6(a) and 6(b), the adhesive tapes 11a and 11b areattached to the inner lead pins 12 so as to substantially form a square.Reference numeral 13 indicates a support bar which is connected to thedie pad of the lead frame. When heated at 300° C. for 3 minutes, thelead frame in the state shown in FIG. 6(a), the distance between thesupport bar 13 and the inner lead pin 12a adjacent thereto (indicated bysymbol A in FIG. 6(a) and by B in FIG. 6(b)) is extended as shown inFIG. 6(b), thus causing deviation of the positions of the inner leadpins. As the result, the wire bonding step in which the semiconductorchips and the inner lead pins are connected to each other cannot beconducted appropriately. This leads a decrease in the efficiency of thewire bonding step during the assembly procedure, or to short-circuitbetween the wirings caused by the shifted inner lead pin contacting theadjacent inner lead pin, resulting in that the semiconductor device isno longer usable.

As stated above, this problem which would otherwise occur can beprevented with the above-described countermeasure according to thepreferred embodiment of this invention.

III. In a still another embodiment of this invention, the adhesive layerfurther contains an organic or inorganic filler.

Examples of the inorganic filler which can be used include pulverizedsilica, molten silica, alumina, titanium oxide, beryllium oxide,zirconium oxide, magnesium oxide, titanium nitride, boron nitride,silicon nitride, titanium boride, tungsten boride, silicon carbide,titanium carbide, zirconium carbide, molybdenum carbide, and thesesubstances treated on their surfaces with a trimethylsiloxyl group orthe like. As the organic filler, there can be cited polyimides, resolphenol resins, epoxy resins, acrylic resins, styrene resins, siliconeresins, nylons, polyamindeimides, polyether-ether-ketones,polyetherimides, polyesterimides, and the like. The organic andinorganic fillers may have an average particle size of from 0.1 to 50μm. However, it is preferred that the maximum particle size thereof doesnot exceed the thickness of the adhesive layer.

In this embodiment, the organic or inorganic filler must be contained inthe adhesive layer in an amount of from 0.5 to 80% by weight based onthe total weight of the adhesive layer. When the amount of the filler isless than 0.5% by weight, the effect of the filler is not obtained. Onthe other hand, the adhesive layer becomes brittle, thus failing to giveappropriate operability when the amount of the filler is more than 80%by weight.

The adhesive layer used in this embodiment can be prepared by mixing theadhesive with the filler by agitating them with a sand mill, three-rollmill, Bambury mixer or the like, or by dispersing them using adisperser, and coating the resulting mixture in a thickness of from 1 to150 μm, preferably from 5 to 50 μm, and curing it to B-stage. Variousthermoplastic resins such as polyether-ether-ketones, polyesters,polyamideimides and the like can be added alone or as a blend with thethermosetting resin.

The addition of the organic or inorganic filler in the adhesive layer isuseful in controlling the dielectric constant and adhesive properties ofthe adhesive used as well as improving the lead shift characteristics asdescribed above.

EXAMPLES

This invention will be described in greater detail with reference to thefollowing examples. However, the invention should not be construed asbeing limited thereto. Unless otherwise indicated specifically, allparts and percentages are by weight.

Example 1

Using materials shown in Table 2 below and methyl ethyl ketone(hereafter, "MEK") as a solvent, adhesive solutions 1 through 8 areprepared which have blend ratios shown in Table 3 below.

                  TABLE 2                                                         ______________________________________                                        Resin    Trade Name  Manufacturer                                             ______________________________________                                        NBR (1)  NB56        Nippon Zeon Co., Ltd. Note 1                             NBR (2)  NIPOL 1001  Nippon Zeon Co., Ltd. Note 2                             Phenol   CKM-908     Showa Kobunshi Kogyo Co., Ltd.                           resin (1)            Note 3                                                   Phenol   Tackirol 201                                                                              Taoka Kagaku Kogyo Co., Ltd.                             resin (2)            Note 4                                                   Phenol   BKM-2620    Showa Kobunshi Kogyo Co., Ltd.                           resin (3)            Note 5                                                   Phenol   KP732 E-2   Arakawa Kagaku Kogyo Co., Ltd.                           resin (4)            Note 6                                                   ______________________________________                                    

Note 1: NBR synthesized by Nippon Zeon Co., Ltd. The polymerizationcatalyst, pH adjusting agent after the polymerization and the like areconsidered. Particularly, the concentrations of calcium ions and ofsulfate ions are lowered. Mooney viscosity: 50, bonded acrylonitrilecontent: 37%.

Note 2: NBR synthesized by Nippon Zeon Co., Ltd. which has the followingproperties: Mooney viscosity: 78, bonded acrylonitrile content: 41%.

Note 3: Bisphenol A resol phenol resin produced by Showa Kobunshi KogyoCo., Ltd., having a softening point of 73° to 90° C.

Note 4: Alkylphenol resol phenol resin produced by Taoka Kagaku KogyoCo., Ltd., having a softening point of 75° to 90° C.

Note 5: Cresol resol phenol resin produced by Showa Kobunshi Kogyo Co.,Ltd., having a softening point of 80° to 100° C.

Note 6: Resol phenol resin produced by Arakawa Kagaku Kogyo Co., Ltd.which is a liquid low molecular weight resin containing phenol typestructure as a basic structure, having the following properties.Volatile component with methanol/isopropyl alcohol: about 3.5%.Viscosity at 25° C.: 245 cps. Gelling time at 140° C. about 8 minutes.

                  TABLE 3                                                         ______________________________________                                        Adhesive                                                                             Blend Ratio of Materials (Parts by Weight)                             solution      NIPOL    CKM  Tackirol                                                                            BKM   KP732                                 Number NB56   1001                                                            908    201    2620     E-2  MEK                                               ______________________________________                                        1      100    --       200  --    --    --    500                             2      100    --       --   200   --    --    500                             3      100    --       --   --    200   --    500                             4      100    --       --   --    --    200   500                             5      --     100      200  --    --    --    500                             6      --     100      --   200   --    --    500                             7      --     100      --   --    200   --    500                             8      --     100      --   --    --    200   500                             ______________________________________                                    

The resulting adhesive solutions 1 through 8 are coated on one surfaceof respective polyimide films having a thickness of 50 μm ("Kapton200H", produced by E. I. Du Pont de Nemours) to a thickness of 20±3 μm,and dried at 150° C. for 5 minutes to prepare adhesive tapes 1 through8. These adhesive tapes are used for measuring electric current leakcharacteristics, and the electric conductivity, concentration of sulfateions and adhesion to the molding compound are measured in theabove-described manner. The results obtained are shown in Table 4 below.

                  TABLE 4                                                         ______________________________________                                                                        Adhesion                                      Adhesive Electric    Concentration                                                                            to Molding                                    Tape     Conductivity                                                                              of Sulfate Ions                                                                          Material                                      Number   (μs/cm)  (ppm)      (kg/1.5 cm)                                   ______________________________________                                        1         40         220        420                                           2         35         200        420                                           3         45         140        420                                           4         80         180        420                                           5        120         960        420                                           6        140         840        420                                           7        130         720        420                                           8        160         660        420                                           ______________________________________                                    

Using the adhesive tapes, the change in the electric currentcharacteristics after PCT tests are measured under the followingconditions.

a. An adhesive tape having a size of 1 mm in width×5 mm in length isattached between the pins to be measured of 100-pin QFP lead frame.

b. The lead frame in a above is molded and dam bar is cut.

c. Voltage of 10V is applied between the pins to be measured, andinitial leak current value is measured.

d. The samples for the measurement are treated with PCT (saturated type,121° C./2 atm.) for 500 hours, and the leak current values after PCT 500hours are measured in the same manner as in c above.

The results obtained are shown in Table 5 below.

                  TABLE 5                                                         ______________________________________                                                   Initial                                                            Adhesive   Current     Current Leak Value                                     Tape       Leak Value  After PCT 500 Hours                                    Number     (A)         (A)                                                    ______________________________________                                        1          1 × 10.sup.-13 or less                                                              1 × 10.sup.-12                                   2          1 × 10.sup.-13 or less                                                              5 × 10.sup.-12                                   3          1 × 10.sup.-13 or less                                                              8 × 10.sup.-10                                   4          1 × 10.sup.-13 or less                                                              4 × 10.sup.-10                                   5          1 × 10.sup.-13 or less                                                              5 × 10.sup.-10                                   6          1 × 10.sup.-13 or less                                                              7 × 10.sup.-9                                    7          1 × 10.sup.-13 or less                                                              5 × 10.sup.-9                                    8          1 × 10.sup.-13 or less                                                              4 × 10.sup.-9                                    ______________________________________                                    

Example 2

Using NBR (1) and Phenol resin (4) shown in Table 2 above as the NBR andresol phenol resins, test adhesive solutions 9 through 12 are prepared.The adhesive solutions are coated on Apical (polyimide film produced byKanegafuchi Kagaku Kogyo Co., Ltd.) and Ultem (polyetherimide filmproduced by Mitsubishi Gas Chemical Co., Ltd.) each having a thicknessof 50 μm so as to form a layer of a dry thickness of 25±5 μm, and driedat 165° C. for 3 minutes to prepare adhesive tapes 9 through 16. Table 6shows the relationship between the heat resistant films used in thesamples and the adhesive solutions.

                  TABLE 6                                                         ______________________________________                                        Adhesive                Adhesive                                              Tape          Name of   Solution                                              Number        Base Film Number                                                ______________________________________                                         9            Apical 50AH                                                                              9                                                    10            Apical 50AH                                                                             10                                                    11            Apical 50AH                                                                             11                                                    12            Apical 50AH                                                                             12                                                    13            Ultem 50 μm                                                                           9                                                    14            Ultem 50 μm                                                                          10                                                    15            Ultem 50 μm                                                                          11                                                    16            Ultem 50 μm                                                                          12                                                    ______________________________________                                    

Adhesive Solution 9:

a. Deionized water (100 parts) is charged in a stainless steel vessel,to which is added 1 part of phenol resin (4). The mixture is stirredwell and the phenol resin component which settles on the bottom of thevessel is collected, and placed in a vacuum drier at 50° C. underreduced pressure to remove water content. MEK (100 parts) is added to100 parts of the phenol resin obtained after the removal of water todissolve it well to obtain a phenol resin solution A.

b. To 100 parts of NBR is added 400 parts of MEK, and the mixture isstirred to well dissolve to obtain an NBR solution A.

c. To 100 parts of NBR solution A is added 250 parts of phenol resinsolution A, and the mixture is well stirred.

d. The NBR-phenol resin mixed solution prepared in c above is introducedin a pressurized reactor, and stirred at 80° C. for 2 hours to obtain anadhesive solution 9. (The ratio of NBR: phenol resin is 100:625 in termsof the solid content.)

Adhesive Solution 10

a. To 100 parts of the NBR solution A used in the preparation ofAdhesive Solution 9 above is added 100 parts of phenol resin solution A,and stirred well.

b. The NBR-phenol resin mixed solution prepared in a above is introducedin a pressurized reactor, and stirred at 80° C. for 2 hours to obtain anadhesive solution 10. (The ratio of NBR: phenol resin is 100:250 interms of the solid content.)

Adhesive Solution 11

a. To 100 parts of the NBR solution A used in the preparation ofAdhesive Solution 9 above is added 20 parts of phenol resin solution A,and stirred well.

b. The NBR-phenol resin mixed solution prepared in a above is introducedin a pressurized reactor, and stirred at 80° C. for 2 hours to obtain anadhesive solution 11. (The ratio of NBR:phenol resin is 100:50 in termsof the solid content.)

Adhesive Solution 12

a. To 100 parts of the NBR solution A used in the preparation ofAdhesive Solution 9 above is added 77 parts of phenol resin solution(4), and stirred well.

b. The NBR-phenol resin mixed solution prepared in a above is introducedin a pressurized reactor, and stirred at 80° C. for 2 hours to obtain anadhesive solution 12. (The ratio of NBR:phenol resin is 100:250 in termsof the solid content.)

The adhesive tapes thus prepared are measured for the electricconductivity of extracted water, concentration of sulfate ions containedin the system, and adhesion strength between the heat resistant film andthe molding compound are measured in the above-described manner. Theresults obtained are shown in Table 7 below.

                  TABLE 7                                                         ______________________________________                                                                         Adhesion                                     Adhesive Electric     Concentration                                                                            to Molding                                   Tape     Conductivity of Sulfate Ions                                                                          Material                                     Number   (μs/cm)   (ppm)      (kg/1.5 cm)                                  ______________________________________                                         9       28           130        420                                          10       23           100        420                                          11       25            70        420                                          12       78           110        420                                          13       18           220        150                                          14       14           180        150                                          15       10           210        150                                          16       40           220        150                                          ______________________________________                                    

Using the adhesive tapes, the change in the electric currentcharacteristics after PCT tests are measured under the same conditionsas in Example 1.

The results obtained are shown in Table 8 below.

                  TABLE 8                                                         ______________________________________                                                  Initial                                                             Adhesive  Current       Current Leak Value                                    Tape      Leak          After PCT 500 Hours                                   Number    (A)           (A)                                                   ______________________________________                                         9        Impossible to measure because of striping off of                              the adhesive layer from the base film.                              10        1 × 10.sup.-13 or less                                                                .sup. 2 × 10.sup.-12 to 8                                               × 10.sup.-12                                    11        1 × 10.sup.-13 or less                                                                1 × 10.sup.-10 to 1 × 10.sup.-9           12        1 × 10.sup.-13 or less                                                                2 × 10.sup.-10 to 3 × 10.sup.-9           13        Impossible to measure because of striping off of                              the adhesive layer from the base film.                              14        1 × 10.sup.-13 or less                                                                1 × 10.sup.-12 to 7 × 10.sup.-9           15        1 × 10.sup.-13 or less                                                                8 × 10.sup.-10 to 5 × 10.sup.-7           16        1 × 10.sup.-13 or less                                                                3 × 10.sup.-10 to 4 × 10.sup.-9           ______________________________________                                    

Example 3

Using materials shown in Table 9 below and MEK as a solvent, adhesivesolutions 13 through 17 are prepared which have blend ratios shown inTable 10 below.

                  TABLE 9                                                         ______________________________________                                        Resin    Trade Name  Manufacturer                                             ______________________________________                                        NBR (3)  NIPOL 1031  Nippon Zeon Co., Ltd. Note 1                             Phenol   CKM-908     Showa Kobunshi Kogyo Co., Ltd.                           resin (1)            Note 2                                                   Phenol   CRM-0803    Taoka Kagaku Kogyo Co., Ltd.                             resin (5)            Note 3                                                   Phenol   KP732 E-2   Arakawa Kagaku Kogyo Co., Ltd.                           resin (4)            Note 4                                                   ______________________________________                                    

Note 1: NBR synthesized by Nippon Zeon Co., Ltd. which has the followingproperties. Mooney viscosity: 63, bonded acrylonitrile content: 41%.Weight average molecular weight/number average molecular weight=4.2

Note 2: Bisphenol A resol phenol resin produced by Showa Kobunshi KogyoCo., Ltd., having a softening point of 70° to 90° C.

Note 3: p-Nonylphenyl resol phenol resin (alkylphenol resol phenolresin) produced by Showa Kobunshi Kogyo Co., Ltd., having a softeningpoint of 82° to 90° c.

Note 4: Resol phenol resin produced by Arakawa Kagaku Kogyo Co., Ltd.which is a liquid low molecular weight resin containing phenol structureas a basic structure, having the following properties. Volatilecomponent with methanol/isopropyl alcohol: about 3.5%. Viscosity at 25°C.: 245 cps. Gelling time at 140° C.: about 8 minutes.

                  TABLE 10                                                        ______________________________________                                        Adhesive                                                                             Blend Ratio of Materials (Parts by Weight)                             solution                                                                             NIPOL     CKM     CRM     KP732                                        Number 1031                                                                   908    0803      E-2     MEK                                                  ______________________________________                                        13     100       150     --      --     500                                   14     100       --      150     --     500                                   15     100       --      --      200    500                                   16     100        20     --      --     500                                   17     100       500     --      --     500                                   ______________________________________                                    

The resulting adhesive solutions 13 through 17 are coated on one surfaceof respective polyimide films having a thickness of 50 μm ("Upilex 50S",produced by Ube Kosan Co., Ltd.) to a thickness of 20 μm, and dried at160° C. for 3 minutes to prepare adhesive tapes 17 through 21.Simulating the taping with adhesive tapes represented by those forfixing lead frame, the adhesive tapes thus-obtained are attached to42-pin 42-alloy lead frame and pressurized for 0.3 second under theconditions of an application size of 1.5 mm in width×10 mm in length ata temperature of 200° C. and a pressure of 4 kg·f/cm² to perform taping.The adhesion strength at room temperature immediately after the tapingand decrease in the adhesion strength after heating at 250° C. for 1hour (hereafter, "adhesion strength after thermal hysteresis") areexamined by measuring the peel strength of the tapes using a universaltesting machine in the manner as shown in FIG. 7. That is, an adhesivetape composed of the heat resistant film 1 having laminated thereon theadhesive layer 2 is attached to a plurality of pins 4 fixed on the leadframe and the adhesive tape is hung on a member for engagement or hook 5positioned between the pins in the central portion of the lead frame asshown in FIG. 7. Then the hook 5 is pulled up in the direction at rightangles to the plane of adhesion to measure the peel strength of theadhesive tapes. The results obtained are shown in Table 11 below.

                  TABLE 11                                                        ______________________________________                                        Adhesive Adhesion at Adhesion                                                 Tape     Room Temp.  After Thermal                                            Number   After Taping (g)                                                                          Hysteresis   Evaluation                                  ______________________________________                                        17       580         570          Fair                                        18       530         610          Fair                                        19       250         190          Poor                                        20       450         580          Poor Surface                                                                  Property                                    21       150         100          Poor                                        ______________________________________                                    

As will be clear from the results in Table 11 above, the adhesive tapes17 and 18 of this invention exhibit sufficient adhesion and fair surfaceproperties. On the other hand, the adhesive tapes of the comparativeexamples 19 and 21 show poor adhesion. The adhesive tape of thecomparative example 20 shows sufficient adhesion but the surface of itsadhesive layer is blocking and the surface property thereof is poor andpractically unacceptable.

Example 4

Using materials shown in Table 12 below and MEK as a solvent, adhesivesolutions 18 and 19 are prepared which have blend ratios shown in Table13 below.

                  TABLE 12                                                        ______________________________________                                        Resin    Trade Name  Manufacturer                                             ______________________________________                                        NBR (4)  DN1031      Nippon Zeon Co., Ltd. Note 5                             NBR (5)  D-8161      Nippon Zeon Co., Ltd. Note 6                             Phenol   BKM-2620    Showa Kobunshi Kogyo Co., Ltd.                           resin (5)            Note 7                                                   ______________________________________                                    

Note 5: NBR synthesized by Nippon Zeon Co., Ltd. which has the followingproperties. Mooney viscosity: 63, bonded acrylonitrile content: 41%.Number average molecular weight: about 73,000. Weight average molecularweight/number average molecular weight=4.15

Note 6: NBR synthesized by Nippon Zeon Co., Ltd. which has the followingproperties. Softening point: 70° to 90° C. Mooney viscosity: 73, bondedacrylonitrile content: 40%. Weight average molecular weight/numberaverage molecular weight=4.15

Note 7: Cresol resol phenol resin (alkylphenol type resol phenol resin)produced by Showa Kobunshi Kogyo Co., Ltd., having a softening point of80° to 100° C.

                  TABLE 13                                                        ______________________________________                                        Adhesive  Blend Ratio of Materials (Parts by Weight)                          solution  DN-                                                                 Number    1031    D-8161     BRM-2620 MEK                                     ______________________________________                                        18        100     --         200      500                                     19        --      100        200      500                                     ______________________________________                                    

The resulting adhesive solutions 18 and 19 are coated on one surface ofrespective polyimide films having a thickness of 50 μm ("Apical 50AH",produced by Kanegafuchi Kagaku Kogyo Co., Ltd.) to a dry thickness of 20μm, and dried at 160° C. for 3 minutes to prepare adhesive tapes 22 and23. Simulating the taping with adhesive tapes represented by those forfixing lead frame, the adhesive tapes thus-obtained are attached to42-pin copper-alloy lead frame and pressurized for 0.3 second under theconditions of an application size of 1.5 mm in width×10 mm in length ata temperature of 200° C. and a pressure of 4 kg·f/cm² to perform taping.The adhesion strength at room temperature immediately after the tapingand decrease in the adhesion strength after heating at 250° C. for 1hour (hereafter, "adhesion strength after thermal hysteresis") areexamined by measuring the peel strength of the tapes using a universaltesting machine in the same manner as in Example 3. The results obtainedare shown in Table 14 below.

                  TABLE 14                                                        ______________________________________                                        Adhesive  Adhesion at Adhesion                                                Tape      Room Temp.  After Thermal                                           Number    After Taping (g)                                                                          Hysteresis   Evaluation                                 ______________________________________                                        22        550         470          Fair                                       23        230         110          Poor                                       ______________________________________                                    

As will be clear from the results in Table 14 above, the adhesive tape22 of this invention exhibits sufficient adhesion as compared with thecomparative adhesive tape 23.

Example 5

On various base films shown in Table 15 is coated an acrylic basedadhesive (Teisan Resin SG-70L, produced by Teikoku Kagaku Sangyo Co.Ltd.) as the adhesive, and the coated base films are dried in a drier inwhich hot air is circulated at 150° C. for 10 minutes to form B-stageadhesive layers of a thickness of 15±2 μm. The adhesive sheets thusobtained are cut to pieces of a size of 20 mm and 17 mm in width,respectively, along the direction of running of the base film (thedirection of the machine) to obtain adhesive tapes, which are used assamples for the measurement of lead shift. Using the adhesive tapes, thelead shift is measured in the following manner. The results obtained areshown in Table 16 below.

(1) Samples

Adhesive tape to be measured is cut to a width of 17 mm or 20 mm alongthe direction of running of the base film (the direction of themachine).

(2) Lead frame to be measured

As the lead frame for measuring the lead shift used 128-pin QFP leadframe. The distance (A) between the portions of the lead frame shown inFIG. 6(a) is measured with a measurement limit of 1 μm prior tomeasurement of the lead shift. The value obtained is named "A".

(3) Taping

Taping is conducted using 4-directional taping machine produced bySumitomo Kinzoku Kozan Co., Ltd. as a lead frame taping machine.

(4) Heat Treatment

The lead frame subjected to the taping is then heat treated at 300° C.for 3 minutes on a hot plate, supposing thermal hysteresis of thesemiconductor devices in the assembly step.

(5) Measurement of Lead Shift

The distance (B) between the portions shown in FIG. 6(b) is measuredwith a measurement limit of 1 μm, and the value obtained is named "B".Then, the lead shift ratio α (%) is calculated according to thefollowing equation. ##EQU1##

                  TABLE 15                                                        ______________________________________                                                                          Thickness                                   Sample   Base Film      Composition                                                                             (μm)                                     ______________________________________                                        1        Upilex S       Polyimide 50                                                   (Ube Kosan)                                                          2        Upilex S       Polyimide 50                                                   (Ube Kosan)                                                                   Treated at 300° C.                                                     for 5 minutes                                                        3        Kapton 200H    Polyimide 50                                                   (Toray Du Pont)                                                      4        Apical 50AH    Polyimide 50                                                   (Kanegafuchi Kagaku)                                                 ______________________________________                                                              Degree of                                                        Coefficient of                                                                             Thermal                                                          Thermal Expansion                                                                          Shrinkage                                               Sample   (cm/cm/°C.)                                                                         (%)        Note                                         ______________________________________                                        1        1.6 × 10.sup.-5                                                                      0.33                                                    2        1.6 × 10.sup.-5                                                                      0.10       Both surfaces                                                                 heat treated                                                                  with infrared                                                                 heater                                       3        3.4 × 10.sup.-5                                                                      0.25                                                    4        3.2 × 10.sup.-5                                                                      0.03                                                    ______________________________________                                    

                  TABLE 16                                                        ______________________________________                                        Sample    Ratio of                                                            Number    Lead Shift                                                                             Evaluation    Note                                         ______________________________________                                        1         11.5     Poor          Comparison                                   2         4.0      Fair          Invention                                    3         14.3     Poor          Comparison                                   4         13.2     Poor          Comparison                                   ______________________________________                                    

The results shown in Table 16 clearly indicate that the sample of thisinvention has low lead shift ratio.

Example 6

On various base films shown in Table 17 is coated a nylon based adhesive(Toresin FS-410, produced by Teikoku Kagaku Sangyo Co. Ltd.) as theadhesive, and the coated base films are dried in a drier in which hotair is circulated at 150° C. for 10 minutes to form B-stage adhesivelayers of a thickness of 25±2 μm. The adhesive sheets thus obtained arecut to pieces of a size of 20 mm and 17 mm in width, respectively, alongthe direction of running of the base film (the direction of the machine)to obtain adhesive tapes, which are used as samples for the measurementof lead shift. Using the adhesive tapes, the lead shift is measured inthe same manner as in Example 5.

The results obtained are shown in Table 18 below.

                  TABLE 17                                                        ______________________________________                                                                         Thickness                                    Sample   Base Film     Composition                                                                             (μm)                                      ______________________________________                                        5        CCLHL800      Glass cloth                                                                             100                                                   (Mitsubishi                                                                   Gas Chemical)                                                                 Treated at 330° C.                                                     for 30 minutes                                                       6        Upilex 50R    Polyimide 50                                                    (Ube Kosan)                                                          7        Kapton 100V   Polyimide 25                                                    (Toray Du Pont)                                                      ______________________________________                                                              Degree of                                                        Coefficient of                                                                             Thermal                                                          Thermal Expansion                                                                          Shrinkage                                               Sample   (cm/cm/°C.)                                                                         (%)        Note                                         ______________________________________                                        5        1.5 × 10.sup.-5                                                                      0.10       Heat treated                                                                  in a drier in                                                                 which hot air                                                                 is circulated                                6        8.2 × 10.sup.-5                                                                      0.63                                                    7        3.2 × 10.sup.-5                                                                      0.12       Heat treated,                                                                 low shrinkage                                                                 grade                                        ______________________________________                                    

                  TABLE 18                                                        ______________________________________                                        Sample    Ratio of                                                            Number    Lead Shift                                                                             Evaluation    Note                                         ______________________________________                                        5         5.9      Fair          Invention                                    6         24.3     Poor          Comparison                                   7         12.1     Poor          Comparison                                   ______________________________________                                    

The results shown in Table 18 clearly indicate that the sample of thisinvention has low lead shift ratio.

Example 7

On base films made of Apical 50AH (polyimide films, thickness: 50 μm,produced by Kanegafuchi Kagaku Co., Ltd.) is coated a mixture of anacrylic based adhesive (Teisan Resin SG-70L, produced by Teikoku KagakuSangyo Co. Ltd.) as the adhesive blended with the filler shown in Table19 below and dispersed therein. The coated base films are dried in adrier in which hot air is circulated at 150° C. for 10 minutes to formB-stage adhesive layers of a thickness of 15±2 μm. The adhesive sheetsthus obtained are cut to pieces of a size of 20 mm and 17 mm in width,respectively, along the direction of running of the base film (thedirection of the machine) to obtain adhesive tapes, which are used assamples for the measurement of lead shift. Using the adhesive tapes, thelead shift is measured in the same manner as in Example 5 except thatthe thickness of the adhesive layer is 5 μm in samples 8 through 11 and0.5 μm in sample 5. The results obtained are shown in Table 20 below.

                  TABLE 19                                                        ______________________________________                                                                       Ratio of                                                                             Method                                  Sample                                                                              Ad-                      Filler of Dis-                                 Number                                                                              hesive   Filler          Added  persion                                 ______________________________________                                         8    Teisan   ZrB.sub.2 -F (Zirconium                                                                       20     Sand mill                                     Resin    boride)                                                              SG70-L   Nippon Shin-Kinzoku                                                           Co., Ltd.                                                       9    Teisan   MBN-250 (Boron nitride)                                                                       20     Sand mill                                     Resin    Mitsui Toatsu Kagaku                                                 SG70-L   Co., Ltd.                                                      10    Teisan   RSG (Magnesium oxide)                                                                         20     Sand mill                                     Resin    Tateho Kagaku Co., Ltd.                                              SG70-L                                                                  11    Teisan   MT-10 (Silica)  20     Sand mill                                     Resin    Tokuyama Soda Co., Ltd.                                                                       20     Sand mill                                     SG70-L                                                                  12    Teisan   Tosva1120 (Silicone                                                                           --     --                                            Resin    resin powder                                                         SG70-L   Toshiba Silicone                                                              Co., Ltd.                                                      ______________________________________                                    

                  TABLE 20                                                        ______________________________________                                        Sample    Ratio of                                                            Number    Lead Shift                                                                             Evaluation    Note                                         ______________________________________                                         8        5.0      Fair          Invention                                     9        4.8      Fair          Invention                                    10        5.2      Fair          Invention                                    11        4.5      Fair          Invention                                    12        5.9      Fair          Invention                                    13        13.2     Poor          Comparison                                   ______________________________________                                    

The results shown in Table 20 above clearly show that the addition ofthe filler reduces the lead shift ratio to a greater extent.

On various base films shown in Table 21 is coated a nylon based adhesive(Toresin FS-410, produced by Teikoku Kagaku Sangyo Co. Ltd.) as theadhesive, and the coated base films are dried in a drier in which hotair is circulated at 150° C. for 10 minutes to form B-stage adhesivelayers of a thickness of 25±2 μm. The adhesive sheets thus obtained arecut to pieces of a size of 20 mm and 17 mm in width, respectively, alongthe direction of running of the base film (the direction of the machine)to obtain adhesive tapes, which are used as samples for the measurementof lead shift. Using the adhesive tapes, the lead shift is measured inthe same manner as in Example 7.

The results obtained are shown in Table 22 below.

                  TABLE 21                                                        ______________________________________                                                                         Thickness                                    Sample   Base Film     Composition                                                                             (μm)                                      ______________________________________                                        14       Kapton 200V   Polyimide 50                                                    (Toray Du Pont)                                                      15       Kapton 200V   Polyimide 50                                                    (Toray Du Pont)                                                      16       Kapton 200V   Polyimide 50                                                    (Toray Du Pont)                                                      17       Upilex 50S    Polyimide 50                                                    (Ube Kosan)                                                          18       Upilex 50S    Polyimide 50                                                    (Ube Kosan)                                                          19       Upilex 50S    Polyimide 50                                                    (Ube Kosan)                                                          20       CCLHL800      Glass cloth/                                                                            100                                                   (Mitsubishi   polyimide                                                       Gas Chemical)                                                        21       CCLHL800      Glass cloth/                                                                            100                                                   (Mitsubishi   polyimide                                                       Gas Chemical)                                                        22       CCLHL800      Glass cloth/                                                                            100                                                   (Mitsubishi   polyimide                                                       Gas Chemical)                                                        ______________________________________                                        Sample                     Filler                                             Number     Filler          Added                                              ______________________________________                                        14         SE-5 (Fused silica)                                                                           30                                                            Tokuyama Soda Co., Ltd.                                            15         SE-5 (Fused silica)                                                                           10                                                            Tokuyama Soda Co., Ltd.                                            16         --               0                                                 17         SE-5 (fused silica)                                                                           30                                                            Tokuyama Soda Co., Ltd.                                            18         SE-5 (fused silica)                                                                           10                                                 19         --               0                                                 20         SE-5 (fused silica)                                                                           30                                                            Tokuyama Soda Co., Ltd.                                            21         SE-5 (fused silica)                                                                           10                                                 22         --               0                                                 ______________________________________                                    

                  TABLE 22                                                        ______________________________________                                        Sample    Ratio of                                                            Number    Lead Shift                                                                             Evaluation    Note                                         ______________________________________                                        14        7.9      Fair          Invention                                    15        9.0      Fair          Invention                                    16        18.6     Poor          Comparison                                   17        8.4      Fair          Invention                                    18        8.8      Fair          Invention                                    19        19.5     Poor          Comparison                                   20        5.2      Fair          Invention                                    21        6.7      Fair          Invention                                    22        16.6     Poor          Comparison                                   ______________________________________                                    

The results shown in Table 22 clearly indicate that the samples 14. 15.17, 18, 20 and 21 of this invention has low lead shift ratios.

What is claimed is:
 1. An adhesive tape for electronic parts,comprisinga pre-shrunk heat resistant base film when subjected to heatfrom 20° to 300° C. having an average coefficient of linear thermalexpansion along the width thereof (as measured according toASTMD-696-44) of from 0.4×10⁻⁵ to 2.5×10⁻⁵ cm/cm/° C. and a coefficientof dimensional change along the width thereof after heating at 300° C.for 3 minutes (as measured according to JIS C2318-6.3.5) being nothigher than 0.15%, and an adhesive layer laminated on at least onesurface of the base film.
 2. An adhesive tape as claimed in claim 1,wherein said heat resistant base film is comprised of a materialselected from the group consisting of glass cloth, polyimide and glasscloth/polyimide and wherein the thickness of said heat resistant basefilm is within a range of 5 to 300 μm and wherein said heat resistantbase film is subjected to a preliminary heat treatment of a temperaturewithin a range of 280° to 360° C.
 3. An adhesive tape as claimed inclaim 2, wherein said preliminary heat treatment comprises passing saidheat resistant base films between a plurality of heated rollers heatedat a temperature within a range of 280° to 360° C. for 1 to 10 minuteswhile keeping the films in contact with the surface of the rollers. 4.An adhesive tape as claimed in claim 2, wherein said preliminary heattreatment comprises the passing of said heat resistant base film for 1to 10 minutes through two opposing infrared heaters to heat said heatresistant base film to a temperature within a range of 280° to 360° C.5. An adhesive tape as claimed in claim 2, wherein said preliminary heattreatment comprises the keeping of said heat resistant base film in adrier, in which the hot air temperature is within a range of 280° to360° C. for 1 to 10 minutes.
 6. An adhesive tape for compensating ashift of a lead pin in electronic parts, comprisinga heat resistant basefilm treated between heated rollers at a temperature of from 280° to360° C. for from 1 to 10 minutes with the film in contact with a surfaceof the rollers to have an average coefficient of linear thermalexpansion along the width thereof at from 20° to 300° C. (as measuredaccording to ASTMD-696-44) of from 0.4×10⁻⁵ to 2.5×10⁻⁵ cm/cm/° C. and acoefficient of dimensional change along the width thereof after heatingat 300° C. for 3 minutes (as measured according to JIS C2318-6.3.5)being not higher than 0.15%; and an adhesive layer laminated on at leastone surface of the base film.
 7. An adhesive tape for compensating for ashift of a lead pin of electronic parts, comprisinga heat resistant basefilm that is previously heat treated to have dimensional characteristicsof an average coefficient of linear thermal expansion along the widththereof at from 20° to 300° C. (as measured according to ASTMD-696-44)of from 0.4×10⁻⁵ to 2.5×10⁻⁵ cm/cm/° C. and a coefficient of dimensionalchange along the width thereof after heating at 300° C. for 3 minutes(as measured according to JIS C2318-6.3.5) being not higher than 0.15%,and an adhesive layer laminated on at least one surface of the basefilm.
 8. An adhesive tape for electronic parts for preventing a shortingof electronic parts due to a lead shift phenomenon caused by thermalhysteresis of a lead frame having multiple lead pins in which positionsof lead pins deviate in response to the lead frame being heated at 300°C. for 3 minutes such that adjacent ones of the lead pins could contacteach other and thereby adversely affect carrying out wire bondings inwhich semiconductor chips and the lead pins are to be connected to eachother, potentially giving rise to short-circuiting between said wirebondings because of the deviations in position of the lead pins,comprising:a heat resistant base film that has been preshrunk by heattreating to have an average coefficient of linear thermal expansionalong the width thereof at from 20° to 300° C. (as measured according toASTMD-696-44) of from 0.4×10⁻⁵ to 2.5×10⁻⁵ cm/cm/° C. and a coefficientof dimensional change along the width thereof after heating at 300° C.for 3 minutes (as measured according to JIS C2318-6.3.5) being nothigher than 0.15%, and an adhesive layer laminated on at least onesurface of the base film.
 9. An adhesive tape for electronic parts forpreventing a misalignment of wire bondings due to a lead shiftphenomenon caused by thermal hysteresis of a lead frame multiple leadpins in, which positions of lead pins deviate in response to the leadframe being heated at 300° C. for 3 minutes such that adjacent ones ofthe lead pins contact each other and thereby adversely affect carryingout wire bonding in which semiconductor chips and the lead pins are tobe connected to each other, potentially giving rise to short-circuitingbetween the wire bondings because of the deviations in position of thelead pins comprisinga heat resistant base film that has been subjectedto heat pre-treatment to have an average coefficient of linear thermalexpansion along the width thereof at from 20° to 300° C. (as measuredaccording to ASTMD-696-44) of from 0.4×10⁻⁵ to 2.5×10⁻⁵ cm/cm/° C. and acoefficient of dimensional change along the width thereof after heatingat 300° C. for 3 minutes (as measured according to JIS C2318-6.3.5)being not higher than 0.15%, and an adhesive layer laminated on at leastone surface of the base film.